Wireless technologies present major advantages in terms of freedom of device placement, portability/mobility, and installation cost reduction, since there is no need for drawing cables and drilling. Thereby, such technologies are particularly attractive for interconnecting, detecting, automation, control or monitoring systems using sensor devices such as light devices, light dimmers, wireless remote controllers, and movement or light detectors, that have to be set up in distant places one from the other and from the devices they control. For example, lighting controls may include rotary/dial dimmer switches, slide dimmer switches, touch pad dimmers or plug-in dimmer switches. The rotary/dial dimmer switches have a knob that can be adjusted from full light to very dim and all brightness measures in between, while the on/off function can be integrated in the knob or processed by a separate button. The slide dimmer switches have a sliding handle that allows adjusting the amount of light and brightness, while the on/off function can be integrated in the handle or processed by a separate button. The touch pad dimmers have light and brightness adjusted by moving his finger on the pad. The plug-in dimmer switches are to be plugged into an outlet, while a lamp is to be plugged into the switch. Light and brightness are controlled through a dial on the plug-in dimmer switch.
One of the drawbacks appearing in networks of the like relates to device powering. Indeed, since the devices are not wired, they cannot anymore receive power necessary for performing all the operations required in the network from the mains or via the connection with the controller. Thus, it has been envisaged to equip such devices with built-in batteries. However, since the devices are quite size-constrained, batteries may not be of a large size, thereby resulting in a reduced device lifetime and then in labour intensive battery replacement, which may be time-consuming.
This issue can be solved by providing self-powered devices, which harvest the energy required for operation and communication from their surroundings such as light, temperature, movement (e.g. rotation, vibration, flow), and electro-magnetic radiation, or from the interaction with the human user.
For example, an electro-dynamic power generator such as ECO 100 can be used to power a dedicated radio transmitter module PTM 200 from EnOcean. Such a generator acts like a common electro-dynamic energy transducer, wherein a magnetic element moves in an energy-harvesting coil after actuation by a spring that can be pushed from outside the device by an appropriate push-button or switch rocker. When the spring is pushed up or down, the generated electrical energy is supplied to the module PTM 200, and a RF telegram including a 32-bit module ID and the polarity of the supply voltage can then be transmitted via the module PTM 200. However, this illustrative solution is optimized for working jointly with the proprietary control technology, which makes the system architecture more complex to design and more costly when choosing to operate with other control technologies. Indeed, gateways are then required for translating from the proprietary control technology into a standard control technology compliant for example with IEEE 802.15.4 and ZigBee standards-based protocols. In addition, the amount of harvested energy is proportional to the speed of change of the magnetic field, which, in turn, is determined by the speed of movement of some parts of mechanics/harvester. The speed of the user action (pressing/releasing/holding) the button is usually not sufficient and not predictable. The focus on optimizing the technical aspects of the design such as mechanics, power harvesting, conversion and storage, and integration with the load (radio), in order to match the amount of energy harvestable from the user action, may lead to sacrifice the usability aspects such as the functionality offered to the user, intuitiveness of controls and ease-of-use of controls (e.g. number and order of steps required as compared with the mains- or battery-powered devices).